The studies done over the past decade regarding amphibian declines and deformities worldwide have sparked an enormous amount of discussion regarding what the cause or causes could be. The most common theories point to ultraviolet radiation, pesticides, parasites, disease, and loss of habitat. But what if the cause is not so one-dimensional? What if the deformities and disappearances are due to second-hand, harder to trace causes...like the combination of chemicals affecting immune function?
A new study at UC Berkeley has shown that perhaps pesticides do play a role in this "amphibicide"...but not in the traditional sense. They propose that it is not merely the effect of one chemical at a time that harms frogs and other amphibians, but the combination of the effects of multiple pesticides from agricultural runoff that leads to the weakening of the organisms' immune systems. According to a January 24 article from the Oakland Tribune, the findings showed that frogs treated to a mix of pesticides at a relatively low testing level (a level similar to what the frogs might actually deal with in the "wild") had the following characteristics:
- [were, on average], 10 to 12 percent smaller than the untreated control group.
- nearly 70 percent...succumbed to a common pathogen that the control group successfully fought off.
- developed holes, or plaques, in their thymus, an organ crucial for suppressing disease.
- had high levels of corticosterone — a hormone, similar to one also found in humans, associated with stress and known to decrease growth and retard development.
Just what does this mean for human pesticide health-related issues? What if the testing we've been doing, applying high amounts of a single chemical directly to test animals, has not been an accurate representation of what we're dealing with on a day-to-day basis...which is, basically, dealing with a mix of pesticides that affects us in ways we never knew were possible?